CVE-2026-2439Network attack vectorHinoki check available

Session hijacking via predictable identifier generation

Published Feb 16, 2026 · Updated Feb 16, 2026

Predictable session identifiers in Bruce Van Allen Concierge::Sessions 0.8.1 through 0.8.4 allow remote attackers to hijack sessions. Concierge::Sessions::Base::generate_session_id runs uuidgen without requiring random mode and silently falls back to Perl rand(). Possession of a guessed identifier is sufficient for unauthorized session access, and the fallback is reached whenever uuidgen fails.

CVSS severity9.8
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Predictable session identifiers in Bruce Van Allen Concierge::Sessions 0.8.1 through 0.8.4 allow remote attackers to hijack sessions. Concierge::Sessions::Base::generate_session_id runs uuidgen without requiring random mode and silently falls back to Perl rand(). Possession of a guessed identifier is sufficient for unauthorized session access, and the fallback is reached whenever uuidgen fails.

The record

CVE
CVE-2026-2439
Published
Feb 16, 2026
Updated
Feb 16, 2026
Vendor
Bruce Van Allen
Product
Concierge::Sessions
Classifications
CWE-338, CWE-340, CAPEC-115, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 16, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 16, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.8.1 <0.8.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Bruce Van Allen · Concierge::Sessionsversion=0.8.1 <0.8.5

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-338Use of Cryptographically Weak Pseudo-Random Number Generator (PRNG)
CWE-340Generation of Predictable Numbers or Identifiers
CAPEC-115Authentication Bypass
T1539Steal Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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